Chikungunya Emergence unit
Status: active - level 1
Last updated on 31 October 2025
Chikungunya: the situation in a nutshell
- Chikungunya is an infectious disease caused by an arbovirus, the chikungunya virus.
- Between 2010 and 2024, no cases had been detected on Réunion Island. Since the beginning of 2025, Réunion Island has recorded nearly 54,340 confirmed locally acquired cases of chikungunya. The end of the epidemic was declared on June 24, 2025, by health authorities.
- Meanwhile, Mayotte is experiencing active virus circulation, with over 1,112 cases reported since the first imported cases and an epidemic phase officially declared on May 27, 2025.
- Finally, between May 1 (the start of enhanced surveillance) and July 15, 2025, 799 imported cases of chikungunya have been identified in mainland France, and 31 locally acquired cases, mainly in the PACA, Corsica, Occitanie, and Auvergne-Rhône-Alpes (AuRA) regions—already affected in previous years—and for the first time in Grand Est and Nouvelle-Aquitaine.
- The ANRS Emerging Infectious Diseases activated a level 1 Emergence cell on 16 January 2025.
Follow the latest scientific news on chikungunya !
As part of the ANRS MIE Emergence programme, the agency publishes a weekly scientific review on chikungunya, providing updates on the most recent research findings.
In particular, you will find in the scientific review available for download:
- a summary of the epidemiological situation ;
- recent scientific articles published in peer-reviewed scientific journals;
- recent articles and press releases;
- a brief overview of epidemiology, virology, clinical aspects, treatment and prevention;
- an update on current research into treatments and vaccines, with an overview of current clinical trials;
- official recommendations from health agencies.
Download the scientific review
Epidemiological situation of chikungunya in Réunion
A major chikungunya epidemic between 2005 and 2006
Chikungunya is an infectious disease caused by an arbovirus, the chikungunya virus (CHIKV). Between 2005 and 2006, Réunion experienced a major chikungunya epidemic, with an estimated 266,000 symptomatic cases, or 34% of the island’s population. The epidemic was also marked by 258 deaths. The end of the epidemic was officially declared in April 2007 [2].
The immunity acquired during this episode (estimated at 38% of the population of Réunion) declined over time, which could partly explain the resumption of chikungunya virus circulation in Réunion in 2024 [3]. After an absence of three years, 5 confirmed cases of chikungunya were reported in Réunion in 2009 [4]. Between 2010 and 2024, no indigenous cases were detected. [5]. This absence of cases came to an end in August 2024, marking a new turning point in the circulation of the chikungunya virus on the island.
More about chikungunyaA resumption of viral circulation since August 2024
Between August 2024 and July 8, 2025, 54 340 autochthonous cases of chikungunya were confirmed by PCR in Réunion Island, along with 28 deaths.
Despite the official end of the chikungunya epidemic on the island, CHIKV transmission is still decreasing but remains active in the majority of municipalities[1].
Epidemiological situation in mainland France
Between May 1st, the start of enhanced surveillance, and July 15th, 2025, 799 imported cases of chikungunya were identified in mainland France. Among these imported cases, 646 came from Réunion Island, 32 from Mayotte, 61 from Mauritius, and 37 from Madagascar, where chikungunya outbreaks are currently ongoing.
The first locally acquired case of chikungunya in mainland France in 2025 was reported in early June in the Gard department. As of July 16th, 2025, a total of 31 locally transmitted cases have been recorded, mainly in the regions of Provence-Alpes-Côte d’Azur, Corsica, Occitanie, and Auvergne-Rhône-Alpes, which had already been affected in previous years, and for the first time in Grand Est and Nouvelle-Aquitaine. The number of transmission clusters highlights the significant risk of local transmission of these viruses in mainland France. Additional cases will likely be identified, including outside the usual transmission areas. [Epidemiological Update of July 16, 2025, SpF]
Bibliography
- Agence Régional de Santé de La Réunion (ARS La Réunion), Update on the chikungunya situation in Réunion, accessed 16 July 2025. https://www.lareunion.ars.sante.fr/point-de-situation-et-plan-orsec-0?parent=16426
- RRenault P, Solet JL, Sissoko D, et al. A major epidemic of chikungunya virus infection on Reunion Island, France, 2005-2006. Am J Trop Med Hyg. 2007 Oct;77(4):727-31. PMID: 17978079.
- Gérardin P, Guernier V, Perrau J, et al. Estimating Chikungunya prevalence in La Réunion Island outbreak by serosurveys: two methods for two critical times of the epidemic. BMC Infect Dis. 2008 Jul 28;8:99. doi: 10.1186/1471-2334-8-99. PMID: 18662384; PMCID: PMC2528011. https://doi.org/10.1186/1471-2334-8-99.
- D’Ortenzio E, Grandadam M, Balleydier E, et al. Sporadic cases of chikungunya, Réunion Island, August 2009. Euro Surveill. 2009 Sep 3;14(35):19324. PMID: 19728980..
- SPF, CHIKUNGUNYA UPDATE, October 2024. https://www.lareunion.ars.sante.fr/media/130599/download
